1. Field of the Invention
This invention relates in general to certain new and useful improvements in lamp substitutes as replacements for phosphor excitable lamps in plural lamp fixtures, and more particularly, to lamp substitutes of the type stated which are effective to replace an operating lamp in a plural lamp fixture without materially affecting operation of the remaining lamp or lamps.
2. Brief Description of the Prior Art
In recent years, there has been an interest in reducing the number of fluorescent lights in multi-fluorescent lamp fixtures in order to reduce energy requirements. The same holds true with the phosphor energizable lamp fixtures such as the fixtures which operate with the so-called cathode discharge lamps. For example, in many office buildings and other forms of commercial installations, it has been found that one or more of the lamps in a multi-lamp fixture can be removed without appreciably reducing the total light output so that inefficiency and eye fatigue does not result. In other words, many commercially available fixtures were constructed so that an excess of light was generated for a given purpose.
Conventional fluorescent lamp fixtures were often constructed to hold and energize two lamps. The ballast and circuitry were designed so that each of said lamps were 180 degrees out of phase. In this way, flicker was canceled out to some extent. Thus, two lights were employed or otherwise lights in pairs were employed to reduce noticeable effects of flicker even though the extra lumen output was not required.
One of the problems involved in removing a lamp, as for example, a fluorescent lamp, from a two lamp fixture was the fact that the ballast was not effective to operate only one of the lamps. Thus, in a two-lamp fixture where a ballast was provided, and one of the lamps was burned out, the other of the lamps would not operate or otherwise operated inefficiently with an excess of power.
In order to obviate these problems, there has been a proposed capacitive operable device which was connected between the terminals of a fluorescent lamp which has been removed in a two fluorescent lamp fixture. This device had an outer body with end caps thereon with the overall size and shape of the lamp it was replacing. The end caps were adapted to comply with sockets on the fixture much in the same manner as the removed bulb. A capacitor was connected between the two end caps internally within the outer body. In this way, the remaining lamp could operate without a substantial loss of lumen output and also minimizing the power factor deterioration. This system is more fully described in U.S. Pat. No. 3,956,665 to Westphal.
Another prior art system for permitting removal of one of the fluorescent lamps in a multi-lamp fixture and using a device connected to the sockets where the lamp has been removed is more fully described in U.S. Pat. No. 4,053,811 to Abernathy. In this case, a non-reactive lamp circuit was employed. However, the device also employed a body with a size and shape similar to the lamp to be removed.
While the devices in each of the aforesaid patents employed a tube with end caps and a terminal, they also suffered from the very substantial disadvantage that they could not be easily repaired. For example, these prior art devices were not designed in a manner where end caps could be easily removed for replacement of the wire or the capacitor if the need should arise, and they were not made of a non-breakable material.
In the various prior art substitutes as for example, the type illustrated in the Westphal patent and the type illustrated in the Abernathy patent, the wire extending across the tube could actually be seen. Any vibration in the room would cause the wire to vibrate and which was highly noticeable to an observer. Moreover, an observer looking at the lamp substitute device almost inevitably noticed a vibration of the wire extending across the lamp substitute in these prior art devices which was rather distracting.
The prior art lamp simulators were all constructed of glass, primarily due to the fact that the glass was made to a pre-cut size for use in the existing fluorescent lamp. Moreover, glass was used in these prior art devices due to the fact that plastic materials would tend to sag when constructed in lengths of six foot or greater. Another significant problem with the prior art lamp simulators is the fact that the construction was quite similar to that of an existing fluorescent lamp, even though it did not have the appearance of an existing fluorescent lamp. As a consequence, the end caps had a dimetral size which was slightly less than the actual size of the bulb itself. At least for purposes of shipment, each individual lamp simulator had to be thereafter shipped in a larger container. This of course materially added to the cost of production and distribution and hence the overall cost of a simulator.
Another one of the problems with these prior art devices is the fact that it was necessary to provide a tube, generally in the shape of the lamp which was removed and which should have end caps with terminals to fit within the sockets of the fixture much in the same manner as the removed lamp. Thus, it was necessary to construct a simulator which actually appeared somewhat similar to that of a lamp which was removed. Not only does this type of construction materially add to the overall cost of the simulator, but it also materially added to cost of shipping.
The present invention obviates these and other problems in the provision of a substitute apparatus for a lamp where a plurality of phosphor excitable lamps are connected in series and which substitute apparatus creates a different current path through the fixture. This enables the substitute apparatus to be of a relatively small size constructed at a low cost and easily packaged for purposes of storage and transportation.